Is that Big Ma'am (Top right) and Kaidou (Top left) there in the color page? http://www.thecoli.com/styles/default/xe...
Yeah, that's Big Mom and presumably Kaido. We can't know for sure though
Yeah, it's definitely Big Mom. Compare the eye on this page to her eye on this page.
As for Kaidou, well, that seems by far the most probable thing. But we don't know. Given that all the Yonkous except for Kaidou are accounted for on that page, it seems incredibly likely that the unknown guy is Kaidou. We just can't be entirely sure. =)